I haven't heard this about the piston on the yfz breaking...... what do you mean by this.... I'm not sure you know what you are talking about, what exactly did you hear?

 

i just raced my buddy's 450r... hmf full system, k&n, 18" kendas with a 15t sprocket
and my mods listed below... i pretty much walked away after 3rd gear...
i raced my other buddy's yfz that is set up the same as the trx... (no cammod either) we raced 4 times... i beat him once... he didnt waste me.. i was within 10 feet of him and slowly catching.... he is also 75 pounds lighter than me...

 

yfz is hella fun, that's all i can say.. [img]i/expressions/face-icon-small-smile.gif[/img]